STEALTHMARK · HEAD TO HEAD

All comparisons ↗

GPT-5.5 vs Kimi K3.1 Pro

Kimi K3.1 Pro leads GPT-5.5 by 25.4 points on StealthMark, 56.7 to 31.3. It leads on all 7 benchmarks with results for both. Kimi K3.1 Pro scores higher on Newton's Mirror, with its largest category advantage in reflections.

See the difference ↘
All results ↗
All results ↗

Overall StealthMark

31.3/100Overall rank 43/53
56.7/100Overall rank 11/53

General Intelligence

26.8/100
53.9/100

Visual Intelligence

36.3/100
62.0/100

Reasoning efficiency

On every task, result quality and reasoning tokens are each compared with all measured models and weighed equally. Each dot is one model.

Single-step reasoning Result quality weighed against reasoning tokens on a single problem

Multi-step reasoning Result quality weighed against reasoning tokens across connected steps, as in agentic workflows

  • GPT-5.5Multi-step reasoning not measured

BENCHMARK BY BENCHMARK

Where each model leads

  • GPT-5.5
  • Kimi K3.1 Pro
  • Other models
  • Median

DATASHEET

Specs and pricing

GPT-5.5 runs 1.7× faster in our speed test. Kimi K3.1 Pro scores higher on StealthMark and is 3× cheaper per output token. Both take about 1.05M tokens of context.

  • GPT-5.5
  • Kimi K3.1 Pro
  • Other models
  • Median
PricePer 1M output tokens, input below
GPT-5.5: $30$5 inputKimi K3.1 Pro: $103× cheaper$2 input
Context windowTokens per request, max output below
GPT-5.5: 1.05MTied128K max outputKimi K3.1 Pro: 1MTied1M max output
Output speedTokens per second, our measurement
GPT-5.5: 1931.7× fastertokens/sKimi K3.1 Pro: 117tokens/s
SizeTotal and active parameters
GPT-5.5: Not disclosedKimi K3.1 Pro: 2.8T104B activeEstimated
Developer
OpenAIMoonshot AI
Released
23 Apr 202623 Oct 2026
Origin
United StatesChina
Input → output
Text, image → textText, image, video → text
Architecture
Not publishedPost-trained version of Kimi K3, a Mixture-of-Experts model

Full datasheets, every price and sourceGPT-5.5 ↗Kimi K3.1 Pro ↗

Anticipating threats and planning ahead. Collect coins while avoiding ghosts. Ghosts move before the player each turn, and collisions cost a life. 3 levels in sequence, up to 66 turns in total. Earlier moves and outcomes carry forward, testing learning across levels.

Kimi K3.1 Pro 61.1/100Rank 10/47

Survived 1 of 3
Foresight: complete playing field
Level 315 ptsTurn 20 / 20

Points per level

LevelGPT-5.5Kimi K3.1 Pro
Level 1Second Thoughts
No run
15 ptsOut of lives
Level 2Pressure Pot
No run
12 ptsOut of lives
Level 3Hide or Flight
No run
15 ptsSurvived

Cooperative planning and learning from experience. Coordinate two robots to push numbered cores onto matching sockets. Pressure plates hold doors open; moving either robot uses one turn. 5 levels in sequence, up to 152 turns in total. Earlier moves and outcomes carry forward, testing learning across levels.

Kimi K3.1 Pro 81.8/100Rank 8/48

Cleared 5 of 5
Latch: complete playing field
Level 519.8 ptsTurn 31 / 40

Points per level

LevelGPT-5.5Kimi K3.1 Pro
Level 1Hold the door
No run
5.2 ptsCleared
Level 2Crossfeed
No run
9.8 ptsCleared
Level 3Relay vault
No run
19.2 ptsCleared
Level 4Passing bay
No run
18.2 ptsClearedFinished early · 3 beacons left
Level 5Second thoughts
No run
19.8 ptsCleared

Newton's Mirror

Same task instructions

Physics, perspective and recursive reflections, tested together. Explore the test ↗

The judgment

GPT-5.5

The paint ordering and separate black bead support part of the physical state, but adhesion and rotational transport remain only partly established. The sweeping cyan arc and long crimson lobes do not clearly communicate the limited time since their respective impacts. The main sphere is too large and too low, and the black bead is below its required projected position. Displaced isolated sphere images, a flattened floor echo and missing recursive, nested and emitter reflections provide little coherent optical structure. The colored paint is excessively bulky for the specified quantities.

Kimi K3.1 Pro

The settled sphere, separate airborne black paint and crimson-before-cyan interaction are supported, with a modest crimson travel overshoot. A shared downward framing displacement remains after accounting for the square canvas. The principal limitation is the reflection system: sparse sphere copies and generic curved bands omit most of the ordered mirror-room structure. Materials receive a small upward revision because bounded bright images and dark bands visibly establish some polish, while soft shading and bulky paint remain separate weaknesses.

Score breakdown

CategoryGPT-5.5Kimi K3.1 Pro
State at 600 ms15.0/2523.5/25
Camera and placement6.0/1510.5/15
Reflections5.0/12026.0/120
Materials and scale6.0/107.0/10
Floor-damage reward0.0/100.0/10

Benchmark task

A spinning metal sphere and paint in a mirrored room test physical reasoning, perspective and consistency across repeated reflections.

Selfie

Different task instructions

Visual construction and creative interpretation.

The judgment

GPT-5.5

Six pale, scaled lobes form a balanced radial arrangement, but they remain separate capsules rather than an interlocking serpent knot. There are no crossings, alternating overlaps, or crisp inner bends; the central hexagon is an isolated outline. Small outward-facing heads sit within the lobes without integrated necks. Soft shading and tidy contours provide some finish, while repetitive oval scales and cartoon faces limit organic credibility.

Kimi K3.1 Pro

The transformed reflection, attentive pose and constellation anatomy clearly communicate introspection. Purposeful fine details enrich a coherent composition. Tubular limbs, crowded lower-body overlaps, shallow depth and limited cast lighting keep the overall execution within the competent range.

Score breakdown

CategoryGPT-5.5Kimi K3.1 Pro
Task & likeness3.0/108.0/10
Anatomy & construction3.0/105.5/10
Space & placement5.0/106.5/10
Light & reflections5.0/106.5/10
Purposeful detail4.5/107.5/10
Artistry & character4.0/107.0/10
Materials & effects4.5/107.0/10
Visual integrity7.0/107.0/10

Benchmark task

GPT-5.5

A pale serpent woven into an interlocking knot tests connected anatomy, repeated structure and readable overlaps. Organic surface detail must work with the overall geometry.

Kimi K3.1 Pro

An imagined creature encounters its reflection. The scene tests original character design, visual self-interpretation and the relationship between a subject and its reflected image.

Mona Lisa

Same task instructions

Precise visual recall and portrait reconstruction.

The judgment

GPT-5.5

The veil, restrained smile, crossed hands and muted landscape establish Mona Lisa references. The oversized frontal face and schematic features weaken likeness and expression, while fingerless tapered hand shapes leave anatomy unresolved. Clean contours and balanced framing provide coherence, but sparse garment detail, broad landscape bands and shallow shading limit the portrait's sophistication.

Kimi K3.1 Pro

A coherent, recognizable interpretation with controlled color and readable landscape layers. Replication is limited by the frontal seated construction, elongated facial proportions and oversized, weakly articulated hands. Smooth shading supplies some volume but little of the reference's subtle expression, fabric structure or atmospheric transitions.

Score breakdown

CategoryGPT-5.5Kimi K3.1 Pro
Task & likeness1.5/105.0/10
Anatomy & construction1.5/105.0/10
Space & placement1.5/105.5/10
Light & reflections2.0/106.0/10
Purposeful detail2.5/105.5/10
Artistry & character1.5/106.0/10
Materials & effects2.0/105.0/10
Visual integrity1.5/106.5/10

Benchmark task

An SVG interpretation of the Mona Lisa tests facial likeness, anatomy and the composition of a familiar portrait.

Beach

Same task instructions

Creativity, perspective and visual beauty.

The judgment

GPT-5.5

The sunset, palms, birds, playful animals and ball clearly establish the requested beach scene. Warm sky gradients and clean silhouettes make it appealing. Animal construction is underdeveloped: torso and limb connections are unclear, especially in the round-eared foreground figure. The dolphin lacks a convincing splash, and broad reflection bands suggest sunset light without resolving its behavior on water.

Kimi K3.1 Pro

A coherent, playful beach illustration with readable animals, an organized composition and an aligned sunset reflection. Connected silhouettes, sand texture and atmospheric effects demonstrate controlled execution. Simplified joints, flattened foreground viewpoints and inconsistent shadows limit anatomical and spatial credibility.

Score breakdown

CategoryGPT-5.5Kimi K3.1 Pro
Task & likeness7.0/108.5/10
Anatomy & construction2.5/105.5/10
Space & placement3.0/105.5/10
Light & reflections3.0/106.5/10
Purposeful detail3.0/106.5/10
Artistry & character3.0/105.5/10
Materials & effects3.0/106.5/10
Visual integrity3.5/107.5/10

Benchmark task

A busy shoreline at sunset tests scene composition, animal forms and the relationship between light and water reflections.

Ground Truth

Same task instructions

Physical reasoning, light and visual reconstruction.

The judgment

GPT-5.5

This benchmark has not been assessed yet.

Kimi K3.1 Pro

This benchmark has not been assessed yet.

Benchmark task

A plank, computer mouse and blueberry in a steel room test physical stability, spatial relationships, materials and lighting.

Raccoon

Same task instructions

Scene composition and interacting subjects.

The judgment

GPT-5.5

The raccoon's masked face, bright hull and sweeping wake make the scene readable and lively. The dog is much less resolved: its head is ambiguous, overlapping brown forms obscure its anatomy, and its paws do not visibly grip the controls. Smooth shapes and cheerful colors provide appeal, but weak steering construction and limited depth keep the drawing uneven.

Kimi K3.1 Pro

The additional comparisons support retaining the assessment. Readable steering, shaped animal contours and purposeful details coexist with simplified joints, a frontal passenger whose seated weight is weakly conveyed, and limited physical lighting. The angled craft establishes more depth than the riding pose resolves.

Score breakdown

CategoryGPT-5.5Kimi K3.1 Pro
Task & likeness3.5/107.0/10
Anatomy & construction3.0/105.5/10
Space & placement4.5/106.0/10
Light & reflections5.0/105.5/10
Purposeful detail3.5/107.0/10
Artistry & character3.0/106.0/10
Materials & effects5.0/106.0/10
Visual integrity3.0/107.0/10

Benchmark task

A jet-ski scene pairs a canine driver with a raccoon passenger. It tests the placement and contact of interacting subjects, along with vehicle construction.

Pelican

Same task instructions

Subject construction and spatial relationships.

The judgment

GPT-5.5

The oversized bill, bright bicycle and sunset create an appealing, recognizable cartoon. Riding mechanics are less convincing: the wing has no clear steering contact, leg attachments are uneven, and feet do not visibly engage pedals. A dark notch complicates the rear neck junction. Clean contours and orderly spokes provide polish, while simplified anatomy and lighting limit depth.

Kimi K3.1 Pro

A characterful coastal illustration with controlled contours and varied feather, accessory and bicycle detail. Layered scenery and subtle shading enrich the presentation. Soft leg articulation, unresolved riding contacts, shallow depth and generalized lighting limit physical precision.

Score breakdown

CategoryGPT-5.5Kimi K3.1 Pro
Task & likeness7.5/108.5/10
Anatomy & construction4.5/107.5/10
Space & placement6.5/106.5/10
Light & reflections6.5/106.5/10
Purposeful detail5.5/107.5/10
Artistry & character5.0/107.5/10
Materials & effects6.0/106.5/10
Visual integrity7.5/107.5/10

Benchmark task

A cycling pelican tests anatomy, riding posture and contact between the bird and the bicycle.